Tackle-block



(No Model.)

J. FRASER.

TAOKLBBLOGK. No. 564,012. Patented July 14, 1896.-

- WITNESSES I v [WVEWT0% UNITED STATES PATENT OFFICE.

JOHN FRASER, OF DETROIT, MICHIGAN.

TACKLE-BLOCK.

SPECIFICATION forming part of Letters Patent No. 564,012, dated July 14, 1896.

Application filed March 4, 1896. Serial No. 581,793. (No model.)

To all whom it may concern:

Be it known that 1, JOHN FRASER, a citizen of the United States, residing at Detroit, in the county of WVayne, State of Michigan, have invented certain new and useful Improvements in Tackle-Blocks; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters of reference marked thereon, which form a part of this specification.

My invention relates to an improvement in tackle-blocks; and it consists in the construction and arrangement of parts hereinafter fully set forth, and pointed out particularly in the claims.

The object of the invention is to provide a pulley-block of simple and substantial construction, in which the arrangement is such as to provide a sure and automatic safety catch or clamp for locking the rope which passes over the sheave of the block so as to hold a hoisted load at any elevation, or pre vent said load from falling through the accidental slipping of the rope, at the same time obviating any undue strain upon the journal of the sheave by clamping the rope against a fixed resistance-block having a grooved face in which the rope is adapted to run, which object is accomplished by the construction illustrated in the accompanying drawings, in which Figure 1 is a side elevation of my improved tackle-block. Fig. 2 is a side elevation showing one side of the shell of the block removed, the rope being withdrawn. Fig. 3 is a like view with the ropein position. Fig. 4 is an enlarged perspective of the block against which the rope is clamped. Fig. 5 is an enlarged perspective of one of the locking-cams.

Referring to the letters of reference, Adesignates the opposed plates, preferably of sheet metal, which form the shell of the pulleyblock, and between which the mechanism is mounted. Between the upper ends of said plates the hook B is secured, said hook being swiveled in a cross-head 13, having trunnions a, which are journaled in said plates. The sheave G is journaled between the plates of the shell upon a suitable shaft 1), whose outer ends are threaded and which pass through the side plates and receive the nuts 0. A11 eyebolt D, for attachment of one end of the rope which is rove through the pulley-blocks, is pivoted upon a suitable pintle 6 between the lower edges of said plates A.

Pivoted between the lateral wings A of the plates A upon suitable pintles f are the locking-cams E and F, respectively, said pintles upon which said cams are pivoted having threaded ends which project through said plates and receive the nuts 1'. Interposed between said cams and secured to one of the plates of the pulley-block is a friction-block G, against which the rope H, which passes around the sheave O, is adapted to be clamped by the action of the cams E and F. The ends of said blockG, as will be seen, are provided with. a flaring groove h, in which the rope H lies, but which permits of the free passage of the rope therethrough.

The cams E and F are hung so as to operate automatically by force of gravity, the natural tendency of the high points of said cams being to swing inward toward the opposite ends of the friction-block G, as shown in Fig. 2, by which arrangement said cams are caused to remain in contact with the rope H, permittin g said rope to run freely over the sheave 0 when traveling in the direction indicated by the arrows, but which immediately bind and wedge said rope against the opposite ends of the block G should the rope start to move in the opposite direction, as said cams are caused to swing inward by a reverse motion of the rope, thereby wedging said rope tightly between the high points of the cams and the opposed ends of said block G, in which opera tion the rope is clamped on each side between the face of the cam and the end of the fixed block G, making a secure and positive lock against a backward movement of the rope, and one that is sensitive and rapid in its operation.

To provide for unlocking the cams so as to permit the rope to travel freely in either direction, there are employed two cords cl, one for each of said cams, to which said cords are attached, respectively, which cords, passing upward through an eye 0 on the outer face of the plate of the tackle-block, depend within reach of the operator, as shown in Fig. 1. By

a downward pull upon these cords the cams are swung free from the rope H, so as to permit it to run freely, as will be well understood. The operation of these cams in looking the rope against backward movement is purely automatic, and enables the hoisted load to be arrested and held at any desired elevation, and by reason of the employment of two of said cams the holding of the rope is always assured, for, should one cam fail from any cause, the other will engage and securely hold the rope from running backward. Should it be desired to lower the load, the cams may be eased therefrom by means of the cords (I, so as to permit the rope to run back as far as desired, when, upon the release of said cords, the cams will again lock the rope against further bacluvard movement. It will be understood that by this means of clamping the rope between the face of the cam and the fixed i'1.*iction-block, instead of clamping the rope between a wedging agent and the periphery of the sheave, the journal of said sheave is relieved from all undue strain, thereby 0bviating the liability of its becoming sprung or worn. It will also be seen that the ends of the friction-block G extend'beyond the line of the periphery of the sheave, whereby,when the rope is clamped against the end of said block, it is not thrown against the periphery of said sheave.

The faces of the locking-cams which engage the rope are provided with oblique depressions t, which stand on an angle coincident with the twist of the rope, thereby adding to the gripping power of said cams and enabling the rope to be eased away gradually; also enabling the cam to operate with equal facilit y upon a four-strand as well as a three-strand rope.

The position of the locking-cams with respect to the ends of the friction-block is such that ropes of various sizes may be used with equal facility. In fact, a rope of the smallest size permissible for the work to be performed will as readily be locked and held from slipping as securely as a rope of the largest size. Having thus fully set forth my invention, what I claim as new, and desire to secure by Letters Patent, is I 1. In a pulley-block, the combination with the shell, of the sheave j ournaled therein, the rope passing over said sheave, the rigid frietion-block. adjacent to said sheave but independent thereof and lying between the lines of rope passing over the sheave, said block having grooved ends which receive said rope, and the locking-earns pivoted adjacent to the ends of said block to lock the rope against the face thereof.

2. In a pulley-block, the combination of the opposed plates forming the shell of the block, the sheave journaled between said plates, the rope passing over said sheave, the frietion-block interposed between said plates adjacent to the sheave, the gravity lockingcams pivoted between said plates adjacent to the end of the friction-block, the cords attached to one side of said cams and passing upward through an eye in one of said plates, thence downward within reach of the operator.

In a pulley-block, the combination of the opposed plates formin the shell of the block, said plates having laterally-extending win the sheave journaled between said plates, the rope passing over said sheave, the frictionblock interposed between said plates adjacent to and below said sheave, the gravitypawls pivoted between the lateral wings of said plates adjacent to the end of said frietion-block, said cams being so hung that the high point of one swings toward and from said friction-block in the upper are of a circle, while the other cam swings toward and from the opposite end of said block in the lower arc of a circle.

4;. In a pulley-block, the combination of the opposed plates forming the shell of the block, the sheave journaled between said plates, the rope passing over said sheave, the opposed locking-cams journaled between the side ex.- tensions of said plate, and the interposed friction-block interposed between said cams, the ends of which block extend beyond the line of the periphery of said sheave.

In testimony whereof I affix my signature in presence of two witnesses.

.l OlliN FRASER.

Vitnesses:

I. PIPER, EDGAR S. WHEELER. 

